Process for the preparation of brightener pigments

Abstract

Process for the preparation of a brightener pigment comprising (a) a water-insoluble urea-formaldehyde resin having a water content of more than or equal to 50% by weight, and (b) a water-soluble fluorescent whitening agent, which process comprises adding together (a), (b) and an inorganic salt, the amount of the inorganic salt being sufficient to effect deposition of the water-soluble fluorescent whitening agent (b) on the water-insoluble urea-formaldehyde resin (a).

1 . A process for the preparation of a brightener pigment comprising
 (a) a water-insoluble urea-formaldehyde resin having a water content of more than or equal to 50% by weight, and   (b) a water-soluble fluorescent whitening agent,   which process comprises   adding together (a), (b) and an inorganic salt, the amount of the inorganic salt being sufficient to effect deposition of the water-soluble fluorescent whitening agent (b) on the water-insoluble urea-formaldehyde resin (a) and   wherein the inorganic salt is sodium sulfate or calcium chloride and the fluorescent whitening agent is of formula (4)   
       
         
           
           
               
               
           
         
         each R 13  is independently from each other hydrogen; —SO 3 M; —O—C 1 -C 4 alkyl; —CN; —Cl; —COO—C 1 -C 4 alkyl or —CON(C 1 -C 4 alkyl) 2 ; 
         M is hydrogen; sodium; potassium; calcium; magnesium; ammonium; mono-, di-, tri- or tetra-C 1 -C 4 alkylammonium; mono-, di- or tri-C 1 -C 4 hydroxyalkylammonium; or 
         ammonium
 di- or tri-substituted by a mixture of C 1 -C 4 alkyl and C 1 -C 4 hydroxyalkyl groups; and 
 
         n 1  and n 3  are each independently of the other 0 or 1. 
       
     
     
         2 . A process according to  claim 1 , wherein the water content of the water-insoluble urea-formaldehyde resin is 50 to 90% by weight. 
     
     
         3 . A process according to  claim 1 , wherein the water content of the water-insoluble urea-formaldehyde resin is 60 to 90% by weight. 
     
     
         4 . A process according to  claim 1 , wherein the water-insoluble urea-formaldehyde resin has a molar ratio of urea to formaldehyde of from 1:1.3 to 2 moles, a particle diameter of from 0.01 to 100 μm and a BET specific surface area of from 2 to 200 m 2 /g. 
     
     
         5 . A process according to  claim 1 , wherein the ratio by weight of inorganic salts to urea-formaldehyde resin is 1:500 to 1:1. 
     
     
         6 . A process according to  claim 1 , wherein the urea-formaldehyde/fluorescent whitening agent suspension is subsequently treated with an emulsion of long-chain alcohols or derivatives thereof, of derivatives of ethylene oxide-alcohols, of paraffin waxes, or of hydrogenated natural or synthetic resins. 
     
     
         7 . A process according to  claim 1 , wherein the brightener pigment is isolated by filtration and no separate drying or milling step is carried out.